package com.doadway.common.page;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;

import javax.xml.bind.PropertyException;

import org.apache.commons.lang.StringUtils;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.executor.ExecutorException;
import org.apache.ibatis.executor.statement.BaseStatementHandler;
import org.apache.ibatis.executor.statement.RoutingStatementHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.mapping.ParameterMode;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.plugin.Intercepts;
import org.apache.ibatis.plugin.Invocation;
import org.apache.ibatis.plugin.Plugin;
import org.apache.ibatis.plugin.Signature;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.property.PropertyTokenizer;
import org.apache.ibatis.scripting.xmltags.ForEachSqlNode;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.type.TypeHandler;
import org.apache.ibatis.type.TypeHandlerRegistry;


@Intercepts({@Signature(type=StatementHandler.class,method="prepare",args={Connection.class})})    
public class PagePlugin implements Interceptor {    
    
    private static String dialect = ""; //数据库方言    
    private static String pageSqlId = ""; //mapper.xml中需要拦截的ID(正则匹配)    
        
    @SuppressWarnings("unchecked")
	public Object intercept(Invocation ivk) throws Throwable {    
        // TODO Auto-generated method stub    
        if(ivk.getTarget() instanceof RoutingStatementHandler){    
            RoutingStatementHandler statementHandler = (RoutingStatementHandler)ivk.getTarget();    
            BaseStatementHandler delegate = (BaseStatementHandler) ReflectHelper.getValueByFieldName(statementHandler, "delegate");    
            MappedStatement mappedStatement = (MappedStatement) ReflectHelper.getValueByFieldName(delegate, "mappedStatement");    
                
            if(mappedStatement.getId().matches(pageSqlId)){ 
            	//拦截需要分页的SQL    
                BoundSql boundSql = delegate.getBoundSql();    
                //分页SQL<select>中parameterType属性对应的实体参数，即Mapper接口中执行分页方法的参数,该参数不得为空    
                Object parameterObject = boundSql.getParameterObject();
                if(parameterObject==null){    
                    throw new NullPointerException("parameterObject尚未实例化！");    
                }else{    
                    Connection connection = (Connection) ivk.getArgs()[0];    
                    String sql = boundSql.getSql();    
                    String countSql = "select count(0) from (" + sql+ ") as tmp_count"; //记录统计    
                    PreparedStatement countStmt = connection.prepareStatement(countSql);    
                    BoundSql countBS = new BoundSql(mappedStatement.getConfiguration(),countSql,boundSql.getParameterMappings(),parameterObject);    
                    setParameters(countStmt,mappedStatement,countBS,parameterObject);    
                    ResultSet rs = countStmt.executeQuery();    
                    int count = 0;    
                    if (rs.next()) {    
                        count = rs.getInt(1);    
                    }    
                    rs.close();    
                    countStmt.close();    
                    //System.out.println(count);    
                    Page page = null;    
                    if(parameterObject instanceof Page){    //参数就是Page实体    
                         page = (Page) parameterObject;    
                         page.setEntityOrField(true);    //见com.flf.entity.Page.entityOrField 注释    
                        page.setTotalResult(count);    
                    }else{  //参数为某个实体，该实体拥有Page属性    
                    	Map<String,Object> map = (HashMap<String,Object>)parameterObject;
//                        Field pageField = ReflectHelper.getFieldByFieldName(map.get("param1"),"page");
                        page  = (Page)map.get("page");
                        if(page!=null){    
//                            page = (Page) ReflectHelper.getValueByFieldName(map.get("param1"),"page");    
//                            if(page==null)    
//                                page = new Page();    
                            page.setEntityOrField(false); //见com.flf.entity.Page.entityOrField 注释    
                            page.setTotalResult(count);    
//                            ReflectHelper.setValueByFieldName(map.get("param1"),"page", page); //通过反射，对实体对象设置分页对象    
                        }else{    
                            throw new NoSuchFieldException(parameterObject.getClass().getName()+"不存在 page 属性！");    
                        }    
                    }    
                    String pageSql = generatePageSql(sql,page);    
                    ReflectHelper.setValueByFieldName(boundSql, "sql", pageSql); //将分页sql语句反射回BoundSql.    
                }    
            }    
        }    
        return ivk.proceed();    
    }    
    
        
    /**  
     * 对SQL参数(?)设值,参考org.apache.ibatis.executor.parameter.DefaultParameterHandler  
     * @param ps  
     * @param mappedStatement  
     * @param boundSql  
     * @param parameterObject  
     * @throws SQLException  
     */    
    @SuppressWarnings("unchecked")
	private void setParameters(PreparedStatement ps,MappedStatement mappedStatement,BoundSql boundSql,Object parameterObject) throws SQLException {    
        ErrorContext.instance().activity("setting parameters").object(mappedStatement.getParameterMap().getId());    
        List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();    
        if (parameterMappings != null) {    
            Configuration configuration = mappedStatement.getConfiguration();    
            TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();    
            MetaObject metaObject = parameterObject == null ? null: configuration.newMetaObject(parameterObject);    
            for (int i = 0; i < parameterMappings.size(); i++) {    
                ParameterMapping parameterMapping = parameterMappings.get(i);    
                if (parameterMapping.getMode() != ParameterMode.OUT) {    
                    Object value;    
                    String propertyName = parameterMapping.getProperty();    
                    PropertyTokenizer prop = new PropertyTokenizer(propertyName);    
                    if (parameterObject == null) {    
                        value = null;    
                    } else if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {    
                        value = parameterObject;    
                    } else if (boundSql.hasAdditionalParameter(propertyName)) {    
                        value = boundSql.getAdditionalParameter(propertyName);    
                    } else if (propertyName.startsWith(ForEachSqlNode.ITEM_PREFIX)&& boundSql.hasAdditionalParameter(prop.getName())) {    
                        value = boundSql.getAdditionalParameter(prop.getName());    
                        if (value != null) {    
                            value = configuration.newMetaObject(value).getValue(propertyName.substring(prop.getName().length()));    
                        }    
                    } else {    
                        value = metaObject == null ? null : metaObject.getValue(propertyName);    
                    }    
                    TypeHandler typeHandler = parameterMapping.getTypeHandler();    
                    if (typeHandler == null) {    
                        throw new ExecutorException("There was no TypeHandler found for parameter "+ propertyName + " of statement "+ mappedStatement.getId());    
                    }    
                    typeHandler.setParameter(ps, i + 1, value, parameterMapping.getJdbcType());    
                }    
            }    
        }    
    }    
        
    /**  
     * 根据数据库方言，生成特定的分页sql  
     * @param sql  
     * @param page  
     * @return  
     */    
    private String generatePageSql(String sql,Page page){    
        if(page!=null && StringUtils.isNotBlank(dialect)){    
            StringBuffer pageSql = new StringBuffer();    
            if("mysql".equals(dialect)){    
                pageSql.append(sql);    
                pageSql.append(" limit "+page.getCurrentResult()+","+page.getShowCount());    
            }else if("oracle".equals(dialect)){    
                pageSql.append("select * from (select tmp_tb.*,ROWNUM row_id from (");    
                pageSql.append(sql);    
                pageSql.append(") as tmp_tb where ROWNUM<=");    
                pageSql.append(page.getCurrentResult()+page.getShowCount());    
                pageSql.append(") where row_id>");    
                pageSql.append(page.getCurrentResult());    
            }    
            return pageSql.toString();    
        }else{    
            return sql;    
        }    
    }    
        
    public Object plugin(Object arg0) {    
        // TODO Auto-generated method stub    
        return Plugin.wrap(arg0, this);    
    }    
    
    public void setProperties(Properties p) {    
        dialect = p.getProperty("dialect");    
        if (StringUtils.isEmpty(dialect)) {    
            try {    
                throw new PropertyException("dialect property is not found!");    
            } catch (PropertyException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
            }    
        }    
        pageSqlId = p.getProperty("pageSqlId");    
        if (StringUtils.isEmpty(pageSqlId)) {    
            try {    
                throw new PropertyException("pageSqlId property is not found!");    
            } catch (PropertyException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
            }    
        }    
    }    
        
}    
